• I. How can you describe animal characteristics?

A. Symmetry describes the general shape of an organism.

Animals exhibit one of three types of symmetry:

1. Asymmetry describes animals which cannot be divided equally using any plane of symmetry.

For example, a sponge is asymmetrical.

2. Radial symmetry describes animals which can be divided equally along several planes, through a central axis. For example, a sea anemone has radial symmetry.

3. Bilateral symmetry describes animals which can be divided equally into mirror images along only one plane. For example, humans have bilateral symmetry.

• B. Regional terms allow scientists to specify the area of the body of an animal. There are four basic regional terms:

1. Dorsal describes the backside of an animal. For example, the shark fin visible from a boat is the dorsal fin.

2. Ventral describes the underside of an animal. For example, a snake slithers on its ventral surface.

3. Anterior describes the front half of an animal, usually nearest the head. For example, the eyes of a frog are in the anterior region.

4. Posterior describes the back half of an animal, usually nearest the tail. For example, the udders of a cow are in the posterior region.

C. Segmentation describes animals with groups of segments (parts) modified for different functions. Segmentation allows a high degree of specialization, and is a typical characteristic of insects.

Dorsal

Anterior

Ventral

Posterior

III. How do different animals achieve the same life functions?

A. Energy/Food-Getting – Animals use specialized structures to capture and ingest food.

1. Annelids (segmented worms) such as the earthworm seem to eat their way through the soil because they suck in organic and other material by expanding their strong pharynx

2. Insects have mouthparts adapted to handle different diets. Mandibles are used as jaws to chew, cut, and tear food.

3. Amphibians (such as frogs) have different feeding structures over the course of one life. Tadpoles are usually filter feeders or herbivores. However, frogs have long, sticky tongues to capture insects.

4. Mammals have teeth adapted to specific diets. For example, herbivores have flat teeth for grinding, while carnivores have sharp teeth for tearing.

• B. Energy/Nutrition - Animals need to capture energy from other organisms because they are heterotrophs. This requires getting food and digesting food (nutrition). Some organisms have a complete digestive system (a tube that runs from mouth to anus) with functional specialization – different parts of the system may be adapted for various functions. Some have an incomplete digestive system (mouth only)

• 1. Annelids use a simple digestive tract that includes an esophagus, crop (which stores food), a gizzard (which grinds food), and an intestine (for absorption). The material that passes through an earthworm is deposited outside the opening of its burrow. In this way, earthworms aerate and enrich the soil.

2. Insects have a very similar digestive system to that of annelids.

3. Amphibians have a more complex digestive system. Food enters at the mouth, moves to the esophagus, then to the stomach containing digestive enzymes. The small intestine continues digestion and absorption of nutrients begins, the large intestine

allows for the absorption of water. Wastes pass to the cloaca for elimination. Accessory organs such as the liver and pancreas secrete digestive chemicals (such as enzymes) which aid in digestion.

4. Mammals have a very similar digestive system to that of amphibians. However, the cloaca is absent. Wastes are stored in the rectum until eliminated through the anus.

C. Energy /Transport - Animals need to deliver the digested food to the cells and move wastes from cells to organs of excretion.

1.Annelids have a closed circulatory system meaning that blood moves through vessels. Blood is pumped throughout the body in one direction using muscular vessels, called aortic arches. The blood carries dissolved gases and nutrients to the cells and picks up waste products from the cells by diffusion.

2. Insects have an open circulatory system meaning blood (usually called hemolymph in insects) flows freely within body cavities where it makes direct contact with all internal tissues and organs. The “heart” is a muscular tube with holes that depends on movement to pump out hemolymph.

• 3. Fish have a closed circulatory system with two chambered heart and single loop circulation

• 3. Amphibians and most reptiles , like annelids, have a closed circulatory system. However, they have a double loop system. The blood is pumped through a pulmonary circuit to the lungs/skin where it is oxygenated. The blood returns to the heart, which pumps the oxygenated blood, through a systemic circuit to the body. The heart is three chambered with two atria (which receive blood) and one muscular ventricle (that pumps the blood). Because the two atria empty into one ventricle, some mixing of

oxygenated and deoxygenated blood occurs. • 4. Mammals have a closed circulatory system and a four

chambered heart which is fully divided into two halves. Blood circulates through two loops/circuits. Oxygenated blood from the lungs is kept separated from the deoxygenated blood

from the rest of the body.

D. Energy / Respiration - Animals need to use the digested, delivered food for cellular respiration in order to produce ATP for cellular energy. Aerobic organisms must get oxygen from the environment and release carbon dioxide back to the environment due to cellular respiration.

1. Annelids obtain oxygen from their environment by diffusion through their moist skin and into the blood stream. They eliminate carbon dioxide in the same way.

2. Insects have no single major respiratory organ. A system of tracheal tubes exchange respiratory gases directly with individual cells using either diffusion or changes in internal pressure produced by body movement. Openings on the surface of the body called spiracles (which can be opened or closed by valves to prevent water loss) lead to the tubular tracheal system.

• 3. Amphibians in their larval form (tadpoles) obtain oxygen from the water by diffusion through their skin and gills, directly into the blood stream. Adult amphibians may also obtain oxygen by diffusion through their skin and the lining of their mouths. However, adult amphibians also have lungs which help with gas exchange in a terrestrial environment. The lungs may also have small sacs called alveoli, which are

wrapped in small blood vessels. This allows for diffusion of gases between the lungs and the blood stream.

• 4. Mammals rely on well developed lungs composed of numerous alveoli for the exchange of gases.

F. Excretion – Processes such as synthesis and digestion produce waste products that may be toxic to the animal’s body. Unless removed, waste products disrupt homeostasis. Excretory structures help animals to balance chemicals (such as pH, glucose concentration and water).

1. Annelids have two excretory structures, called nephridia, per segment. The nephridia gather wastes from the body cavity and surrounding blood vessels. The waste is excreted through a pore in the following segment.

2. Insects eliminate wastes by collecting circulatory fluid in long spaghetti-like tubules called Malpighian tubules, which extend throughout most of the abdominal cavity. The tubules remove nitrogenous wastes from the hemolymph and convert it to uric acid. The ability to conserve water by excreting solid uric acid has enabled insects to colonize very arid environments.

3. Amphibians use organs called kidneys that are composed of nephrons to filter wastes from blood. This waste, called urine, passes to tubes called ureters, which lead to the cloaca. Urine may be stored in a urinary bladder or passed immediately.

4. Mammals also rely on two kidneys composed of nephrons to filter wastes from the blood. From each kidney there is a ureter tube which leads to the urinary bladder. The urine is then expelled from the body through the urethra.

• I. Regulation – Animals must control necessary body processes (such as metabolism) using the nervous system and endocrine system (which produces hormones). Hormones are chemical messengers that can control target cells or tissue.

1. Annelids have an anterior “brain” with ganglia extending to each body segment. A ganglion is a cluster of interconnected neurons (nerve cells) that process information and control movement. The nerves are used to coordinate muscle contractions for movement. Earthworms have numerous light-, chemo-, and touch- sensitive cells near the end of the body. Hormones are involved in growth, regeneration, and reproduction.

• 2. An insect’s nervous system is composed of neurons within the body. These cells are grouped in bundles called ganglia and nerves. Insects have a relatively simple central nervous system with a “brain” linked to nerve cord that consists of paired ganglia. Insects use special cells in the body to produce hormones which regulate processes such as molting and metamorphosis.

3, Amphibians have a more complex central nervous system. Areas of the brain are specialized to regulate certain processes, such as the olfactory bulb (smell), optic lobes (vision), cerebrum (voluntary activity), cerebellum (coordinates body movement), and medulla oblongata (regulate organ function). Like insects, amphibians have developed sense organs . Like all vertebrates, amphibians have an endocrine system that works with the nervous system to maintain internal conditions, react to stimuli, and regulate growth and development.

4. Mammals have the most highly developed nervous system. The system is divided into a central nervous system (composed of the brain and spinal cord) and the peripheral nervous system (composed of nerves and sensory receptors). In addition to specialized areas of the brain, the brain is larger and can coordinate and store more information. The increase in complexity leads to more advanced sensory ability, communication, and learning. Like amphibians, mammals depend on an endocrine system to work with the nervous system and release hormones for regulation.

IV. How does the form of structures affect their function?

A. Microvilli in the Small Intestine

1. The purpose of the small intestine is to absorb nutrients. The food has been chewed in the mouth, broken down by enzymes in the mouth and stomach, processed by peristalsis (movement through the esophagus) and churned in the stomach. The small intestine must now absorb the products of digestion into the blood stream for delivery to cells.

2. Microvilli in the small intestine are finger-like projections that increase surface area. Increasing surface area allows more physical space for absorption of the nutrients, increasing the efficiency of digestion.

3. Diagram of Microvilli

B. Chambers of the Vertebrate Heart

1.The purpose of the heart is to pump blood to and from the lungs and then throughout the body. Blood acts as the vehicle for many things in our body (such as nutrients, wastes, and hormones) and the circulatory system is the “highway” for this vehicle. One of the major functions of blood is to deliver oxygen to the cells and to remove carbon dioxide from the cells. In a vertebrate’s body, there is blood which contains oxygen (oxygenated blood) which must be delivered to the cells and blood which does not (deoxygenated blood) which is sent to the lungs.

2. A heart contains chambers which separates the deoxygenated blood from the oxygenated blood. By separating the blood, the heart can more efficiently deliver the correct blood to the correct location.a. Fish have a simple two-chambered heart.b. Amphibians and most reptiles have a three-chambered heart.c. Crocodiles, aves, and mammals have a four-chambered heart.

3. The heart is composed of muscle to provide strength as it pumps the blood through the circulatory system. The chamber which must send the blood to the entire body (left ventricle) has a much thicker layer of muscle. This allows that chamber to better perform its function.

4. Diagram of a four-chambered heart

C. Alveoli in the lungs 1. The purpose of the lungs is gas exchange.

Oxygen is taken in and carbon dioxide is released. The oxygen is needed for cell respiration (which makes ATP to use for cell energy) and the carbon dioxide is a waste product produced during cell respiration. The oxygen has to enter the blood supply, and the carbon dioxide has to be removed from blood.

2. The diffusion of gas happens best across a thin, moist membrane. Air enters the body through the nose and mouth, moves through the trachea into the lungs via the bronchi and then into smaller tubes called bronchioles. At the end of each bronchiole, a structure called the alveoli provides a very thin (one cell thick) and moist membrane surrounded by capillaries (some with deoxygenated blood and some with oxygenated).

3. Diagram of alveoli

.

D. Kidney Structure

1. The purpose of kidneys is to remove wastes from blood, maintain blood pH, and

regulate water content of blood. Kidneys form urine (result of filtration) which can be passed from the body.

2.Kidneys are composed of many smaller units called nephrons. As the fluid part of blood (containing waste) is pushed into a nephron (called the “filitrate”), the nephron removes urea, excess water, and other waste products. The clean, filtered blood leaves the kidney through the renal vein and returns to circulation.

3. The nephron is composed of a looping tube that provide a great deal of surface area for diffusion and active transport of molecules into and out of the filtrate as urine is formed.

E. Neuron Structure

1. The purpose of the nervous system is to sense, process, and respond to stimuli. The basic structure which allows the nervous system to perform its function is the neuron (nerve cell). In less complex animals, the nervous system may consist of a nerve net or small clusters of nerves called ganglion. More complex animals have a central processing center (a brain) in addition to the neurons.

2. A neuron uses chemicals (called neurotransmitters) or electricity to send a message to the next neuron in the chain. The shape of a neuron allows it to quickly receive a message through branched dendrites which “charges” the axon to release a message through the axons for the next neuron.

3. Sensory receptor neurons are usually associated with structures specialized for receiving a specific type of stimuli (ex. tastebuds). Interneurons transmit this “message” to a processing center (such as the brain). A motor neuron activates a muscle cell to respond to the stimuli.

• 4. Diagram of a Neuron

Axon terminalsDendritesAxon

Endocrine control• Hormones – chemicals that are produced by the endocrine

gland and released directly into the bloodstream.• Some Endocrine Glands:• Pituitary• Thyroid• Adrenals• Pancreas• Testes• Ovaries